1. Field
Embodiments described in the present specification relate to a semiconductor memory device configured as an arrangement of memory cells each storing data by a change in resistance value of a variable resistance element.
2. Description of the Related Art
In recent years, resistance varying memory devices that employ a variable resistance element as a storage element have been receiving attention as successor candidates of flash memory. Resistance varying memory devices are assumed here to include not only resistance varying memory in a narrow sense, that is, resistance varying memory that configures a transition metal oxide as a recording layer and stores a resistance value state of the transition metal oxide in a nonvolatile manner (ReRAM: Resistive RAM), but also phase change memory that employs chalcogenide or the like as a recording layer and uses resistance value information of a crystalline state (conductor) and an amorphous state (insulator) of the chalcogenide or the like (PCRAM: Phase Change RAM), and so on.
A memory cell array in a resistance varying memory device has memory cells disposed at intersections of bit lines and word lines, each memory cell being configured from a variable resistance element and a current rectifier element such as a diode or the like. In such a memory cell array, selection of a memory cell can be performed using the current rectifier element such as a diode or the like. Moreover, it is also possible for a high-density memory cell array to be realized by alternately stacking the bit lines and word lines to configure a three-dimensional stacked arrangement of memory cell arrays.
In the case of such a memory cell array, characteristics of the variable resistance element or the current rectifier element sometimes deteriorate due to effects from a material employed as an interlayer insulating film or due to repeatedly performed operations, and so on. In that case, there is a possibility of a leak current occurring in the diode when the diode is off, or of effects such as deterioration of switching characteristics of the variable resistance element arising, whereby desired operations on the memory cells cannot be executed.